Damper, especially for movable furniture parts

ABSTRACT

A damper has a cylinder and a piston, the piston having two or more parts. A first piston part consists of a rubber-elastic material forced against the cylinder wall during a damping stroke. A second piston part consists of a material that is stiffer in comparison to the rubber-elastic material. The second piston part as seen in the radial direction lies between an area of the first piston part and the cylinder wall. The first piston part may have at least two sections of different hardnesses over its lengths. The piston could also include a piston part that is radially forced outwards to rub against the cylinder wall during damping, the piston part being made as a solid body of a material with rubber-elastic properties which becomes flattened under pressure, deforming in such a way that a friction seal is created between the piston part and the cylinder wall.

BACKGROUND OF THE INVENTION

The invention relates to a damper, especially for movable furnitureparts, with a cylinder and a piston movable therein, in which the pistoncomprises two or more parts, wherein a first piston part consists ofrubber-elastic material which is forced against the cylinder wall duringthe damping stroke, and wherein a second piston part consists of amaterial which is stiffer in comparison to the rubber-elastic material,especially a rigid material.

SUMMARY OF THE INVENTION

It is object of the invention to improve the braking behaviour of thepiston of such a damper and to reduce its wear.

The object of the invention is met in that the second piston part—seenin radial direction—lies between an area of the first piston part andthe cylinder wall.

One embodiment of the invention provides that the first piston part istaken up in a frontal recess of the second piston part.

In a further embodiment of the invention, provision is made that thefirst piston part has a snap ring groove in the area adjacent to thesecond piston part.

A further embodiment of the invention makes provision that the secondpiston part encircles the mantle of the first piston part in the mannerof a belt, whereby for preference the second piston part is designed asa network which encircles the first piston part.

A further preferred embodiment of the invention makes provision that thefirst piston part has at least two, preferably more, sections ofdifferent hardness over its length.

A further preferred embodiment of the invention provides that the pistonis produced in the form of a solid body made from a material withrubber-elastic properties and becomes flattened under pressure wherebyit deforms in such a way that a friction seal is created between thepiston part and the cylinder wall.

DESCRIPTIONS OF THE DRAWINGS

Various embodiments of the invention will be described with the aid ofthe figures in the attached drawings, which show:

FIG. 1 a side view of an inventive damper,

FIG. 2 a section along line A-A of FIG. 1,

FIG. 3 section A from FIG. 2,

FIG. 4 a side view of an inventive damper after damping has beeneffected,

FIG. 5 a section along line B-B of FIG. 4,

FIG. 6 section A from FIG. 5,

FIG. 7 a section along line A-A of FIG. 1, wherein a further embodimentof a piston is shown,

FIG. 8 section A from FIG. 7,

FIG. 9 a section along line A-A of FIG. 1, wherein a further embodimentof a piston is shown,

FIG. 10 section A from FIG. 9,

FIG. 11 a section along line A-A of FIG. 1, wherein a further embodimentof a piston is shown,

FIG. 12 section A from FIG. 11,

FIG. 13 a section along line A-A of FIG. 1, wherein a further embodimentof a piston is shown,

FIG. 14 section A from FIG. 13,

FIG. 15 a section along line A-A of FIG. 1, wherein a further embodimentof a piston is shown,

FIG. 16 section A from FIG. 15,

FIG. 17 a longitudinal section through a cylinder and a piston, showingthe piston in the ready position,

FIG. 18 a longitudinal section through a cylinder and a piston, showingthe piston in the damping position,

FIG. 19 a schematically shown section through a further embodiment of aninventive damper, showing the piston in the ready position,

FIG. 20 a schematically shown section through the inventive damper,showing the piston during damping,

FIG. 21 a schematically shown section through the inventive damper,showing the piston at the end of the damping path once damping has beencompleted,

FIG. 22-24 similar views of FIG. 19 to 21 of a second embodiment of thepiston,

FIG. 25 a view of a piston in the ready position and

FIG. 26 a view of the piston during the damping process.

In the following the embodiments will be described in accordance withFIG. 1 to 18:

The inventive damper consists in conventional manner of a cylinder 1 inwhich a piston 2 is linearly displaceable. The piston 2 in theembodiments according to FIGS. 1 to 16 consists of a first piston part 3made from a rubber-elastic material and a second piston part 4 made froma harder material than the first piston part 3. The second piston part 4can be made from a plastic, or else from a die-cast alloy or similar. Inthe embodiments shown, the second piston part 4 is designed integralwith a piston rod 5. The piston rod 5 has ribs 6, which improve theguidance of the piston rod 5 in the cylinder 1 and thereby keep thefriction between the piston rod 5 and the cylinder 1 low. The firstpiston part 3 has a lip 7 on its end furthest away from the secondpiston part 4. The front wall 1′ of the cylinder 1 is provided with anopening 8 which enables the escape of a damping fluid, in this case air,during damping.

The first piston part 3 has a peg-type projection 9 in which it isanchored in the second piston part 4. The projection 9 is provided witha spread ring 10, which is taken up in a chamber-shaped recess 11 in thesecond piston part 4. The projection 9 is axially displaceable in therecess 11 with its spread part 10. The first piston part 3 and thesealing lip 7 are preferably made from a rubber-elastic material, forexample from liquid silicon rubber (LSR), thermoplastic elastomer (TPE)or silicon rubber. The range of hardness of the first piston part 3preferably lies between 40 A and 85 A Shore.

The second piston part 4 has a three-dimensionally curved frontal recess13, which is designed at least approximately in the form of a sphericalcap. The first piston part 3 is taken up with its end in this recess 13.The end 14 of the first piston part 3 can be designed eithercylindrically or as a truncated cone.

In the ready position, i.e. when no force is acting upon the piston rod5 and thus the second piston part 4 is not being forced against thefirst piston part 3, the end 14 of the first piston part 3 does notcompletely fill the recess 13. As can be seen, for example, from FIG. 3,the end 14 of the piston part 3 protrudes over approximately half theradius of the recess 13 into the recess 13.

If a force is exerted on the end 12 of the piston rod 5, the piston rod5 and the piston 2 are moved in the direction of the arrow F. Due to theresistance of the damping medium, for example air, the first piston part3 is compressed by deformation during the damping process as in FIGS. 5and 6 and thereby radially expanded, as the result of which a frictionseal is created between the piston part 3 and the cylinder wall 15. Theresistance of the damping medium is increased by the sealing lip 7,which abuts on the cylinder wall 15 from the start of the motion of thepiston.

During this damping motion, the end 14 of the first piston part 3 ispressed into the recess 13, until, as shown in FIGS. 5 and 6, it istaken up more or less completely in the recess. Due to the fact that theend 14 of the first piston part 3 is taken up in the recess duringdamping, the first piston part 3 is deformed and the friction forcesbetween the first piston part 3 and the cylinder wall 15 are distributedover the entire length of the piston part 3. Thus peak forces areprevented in the area where the first piston part 3 rests on the secondpiston part 4. The first piston part 3 is advantageously taperedconically from the sealing lip 7 towards the end 14, which additionallycontributes to a distribution of the friction forces.

In the embodiment according to FIGS. 7 and 8, the first piston part 3 isprovided with a snap ring groove 16 near its end 14. The snap ringgroove 16 contributes to the further unloading of the friction forces inthe rear area of the first piston part 3. It is essential that duringthe entire damping, a part of the second piston part 4, which is theharder piston part, seen in radial direction, lies between the end 14 ofthe softer first piston part 3 and the cylinder wall 15. The softerpiston part 3 thus cannot be forced against the cylinder wall 15 overits entire length.

In the embodiment according to FIGS. 9 and 10, the first piston part 3comprises two sections 3′, 3″ of different hardnesses. The section 3″lying nearer to the lip 7 gives way more quickly when it is made from asofter material. The intended result of this is that the entire surfaceof the piston part 3 abuts against the cylinder wall 15 right from thestart of the braking process. This effects a more even distribution offorce over the piston part 3. This results in smaller peak forces duringthe braking process and less wear.

In the embodiment according to FIGS. 11 and 12, the piston part 3 isprovided with a cavity 18, which is located in its rear area, i.e.facing towards the piston part 4. The cavity 18 allows a targetedinfluence on the surface pressure, thus the distribution of frictionforce over the piston part 3. The surface pressure is reduced at thesite of the cavity 18. Should, for example, the intention be for wear tobe minimised by a harder elastomer as material for the piston part 3,the annular gap between the piston part 3 and the cylinder wall 15 mustbe selected to be very small, since harder materials become effectivelater during the damping process. If no cavity 18 is provided, the smallannular gap between the piston part 3 and the cylinder wall 15 can leadto an abrupt braking at the end of the braking/damping path. The resultwould be an unpleasant braking process.

Instead of a cavity 18, a filling with a softer material could also beprovided.

In the embodiment according to FIGS. 13 and 14, the first piston part 3is provided with a mantle area 19 tapering conically towards the sealinglip 7. On its end facing towards the second piston part 4, the firstpiston part 3 has a cylindrical graduation 20. By greater or lesserconicity of the area 19, the surface pressure can be decreased orincreased in a controlled fashion over the length of the piston part 3.The graduated section 20 prevents any excessive surface pressure in thearea of attachment to the second piston part 4.

In the embodiment according to FIGS. 15 and 16, the first piston part 3has several snap ring grooves 21 and several piston lands 22, whichalternate over the entire length of the piston part 3. The diameters ofthe piston lands 22 here decrease from the sealing lip 7 to the secondpiston part 4. In the embodiment according to FIGS. 17 and 18, thepiston part 3 is encircled by a network 23. The network 23 is made froma harder material than the piston part 3 and forms the second pistonpart. The first piston part 3 rests directly on a bolster plate 24 whichis connected with a piston rod 25. During the damping process, as can beseen from FIG. 18, bulges 26 of the piston part 3 are pressed againstthe cylinder wall 15.

In all embodiments, a more even surface pressure of the piston part 3 onthe cylinder wall 15 is achieved. This causes less wear and a betterbraking behaviour, i.e. the braking behaviour is less abrupt.

In the embodiment according to FIG. 19 to 24, the cylindrical pistonpart 3 abuts against a piston part 4 which is designed as a bolsterplate. In the cylinder 1 there is a compression spring 27, which rests,firstly, on one front wall 1′ of the cylinder 1 and secondly on thefront side of the piston 2. The piston part 4 is connected with a pistonrod 5. The piston part 3 is provided at the front with a sealing lip 7,which abuts on the cylinder wall 15. The term “at the front” means inthe direction of motion of the piston 2 during the damping process.

The front wall 1′ of the cylinder 1 has, in turn, an opening 8, whichallows the escape of the damping fluid, in this case, air.

During the damping process, a force acts on the end 12 of the piston rod5 and the piston 2 is moved in the direction of the arrow F.

Due to the resistance of the damping medium, for example air, the firstpiston part 3 is flattened during the damping process as shown in FIG.20 and thereby radially expanded, as the result of which a friction sealis created between the piston part 3 and the cylinder wall 15.

At the end of the damping path, the piston part 3 expands in the axialdirection due to its own elasticity, whereby the compression spring 27is further compressed.

Since the friction seal between the piston part 3 and the cylinder wall15 is cancelled out due to this axial expansion of the piston part 3,the compression spring 27 of the piston 2 can move back into the readyposition.

In the embodiment according to FIG. 19 to 21, the piston part 3 and thesealing lip 7 form a monolithic body. The piston part 3 and the sealinglip 7 are in this instance made from a rubber-elastic material, forexample from liquid silicon rubber (LSR), thermoplastic elastomer (TPE)or silicon rubber. The range of hardness of the piston preferably liesbetween 40 A and 85 A Shore.

In the embodiment according to FIG. 22 to 24, the piston part 3 and thesealing lip 7 consist of different materials. However, the sealing lip 7is joined to the piston part 3, for example glued or welded, so that thepiston part 3 and the sealing lip 7 can be regarded in functional termsas one piece. The advantage of this execution can be seen in that thepiston part 3 and the sealing lip 7 can have different elasticproperties.

As can be seen from FIGS. 25 and 26, the piston part 3 can be providedwith a groove 28 on the mantle, which enables the through-flow of thedamping fluid within the cylinder 1 from one side of the piston 2 to theother side of the piston 2 during the damping process.

The inventive damper can be used, for example, in drawers, furnituredoors or hatches. It can advantageously be combined with a retracting orclosing device as described in the German utility model DE 202 18 067.

1. Damper with a cylinder and a piston movable therein, in which thepiston comprises two or more parts, wherein a first piston part consistsof rubber-elastic material which is forced against the cylinder wallduring the damping stroke, and wherein a second piston part consists ofa material which is stiffer in comparison to the rubber-elasticmaterial, characterised in that the second piston part—seen in radialdirection—lies between an area of the first piston part and the cylinderwall.
 2. Damper according to claim 1, characterised in that the damperis employed with movable furniture parts.
 3. Damper according to claim1, characterised in that the material of the second piston part is arigid material.
 4. Damper according to claim 1, characterised in thatthe first piston part is taken up in a frontal recess of the secondpiston part.
 5. Damper according to claim 4, characterised in that therecess is three-dimensionally curved.
 6. Damper according to claim 4,characterised in that the recess is realised at least approximately inthe form of a spherical cap.
 7. Damper according to claim 4,characterised in that the first piston part, only partly fills therecess in unpressurised conditions and at least approximately completelyfills it during damping.
 8. Damper according to claim 1, characterisedin that the second piston part is located between the first piston partand a piston rod, which serves as ram.
 9. Damper according to claim 1,characterised in that the mantle of the first piston part describes atleast one cone.
 10. Damper according to claim 9, characterised in thatthe cone tapers towards the second piston part.
 11. Damper according toclaim 9, characterised in that the cone tapers towards the distal end ofthe first piston part in relation to the second piston part.
 12. Damperaccording to claim 1, characterised in that the first piston part, onits end near the second piston part, is graduated in form.
 13. Damperaccording to claim 1, characterised in that the first piston part, onits end near the second piston part, is provided with a snap ringgroove.
 14. Damper according to claim 1, characterised in that the firstpiston part is provided with several snap ring grooves distributed alongits length, between which there are piston lands.
 15. Damper accordingto claim 14, characterised in that the diameters of the piston landsreduce towards the second piston part.
 16. Damper according to claim 1,characterised in that the first piston part has a peg-type projection,by means of which the first piston part is anchored to the second pistonpart.
 17. Damper according to claim 16, characterised in that thepeg-type projection (9) is axially displaceable in the second pistonpart.
 18. Damper according to claim 1, characterised in that the secondpiston part encircles the mantle of the first piston part in the mannerof a belt.
 19. Damper according to claim 18, characterised in that thesecond piston part is designed as a network which encircles the firstpiston part.
 20. Damper according to claim 1, characterised in that thefirst piston part has a cavity in the area adjacent to the second pistonpart, which extends over less than half the length of the first pistonpart.
 21. Damper according to claim 1, characterised in that thehardness of at least a first piston part lies between 40 A and 85 Shore.22. Damper according to claim 1, characterised in that the second pistonpart is designed as a bolster plate for the first piston part which isconnected with a piston rod.
 23. Damper according to claim 1,characterised in that the first piston part is provided with a sealinglip.
 24. Damper according to claim 23, characterised in that the sealinglip abuts against the cylinder wall.
 25. Damper according to claim 23,characterised in that the first piston part and the sealing lip jointlyform a monolithic body.
 26. Damper according to claim 23, characterisedin that the first piston part and the sealing lip are made from plasticswith different hardnesses.
 27. Damper according to claim 23,characterised in that the first piston part and the sealing lip arewelded together.
 28. Damper according to claim 23, characterised in thatthe first piston part and the sealing lip are glued together.
 29. Damperaccording to claim 1, characterised in that at least a piston part isprovided with a groove running in axial direction on its mantle. 30.Damper according to claim 1, characterised in that the first piston partis cylindrical in form in unpressurised condition and the mantle of saidpiston part adopts a domed shape under pressure.
 31. Damper according toclaim 1, characterised in that a compression spring is disposed in thecylinder, said spring rests, firstly, on one front wall of the cylinderand secondly on at least a piston part, wherein the force of expansionof the elastic piston part is greater than the spring force of thecompression spring.
 32. Damper with a cylinder and a piston movabletherein, in which the piston comprises two or more parts, wherein afirst piston part consists of rubber-elastic material which is forcedagainst the cylinder wall during the damping stroke, and wherein asecond piston part consists of a material which is stiffer in comparisonto the rubber-elastic material, characterised in that the first pistonpart has at least two sections of different hardness over its length.33. Damper according to claim 32, characterised in that the damper isemployed with movable furniture parts.
 34. Damper according to claim 32,characterised in that the material of the second piston part is a rigidmaterial.
 35. Damper according to claim 32, characterised in that thefirst piston part has more than two sections of different hardness overits length.
 36. Damper according to claim 32, characterised in that thehardness of at least a piston part lies between 40 A and 85 Shore. 37.Damper according to claim 32, characterised in that the second pistonpart is designed as a bolster plate for the first piston part which isconnected with a piston rod.
 38. Damper according to claim 32,characterised in that the first piston part is provided with a sealinglip.
 39. Damper according to claim 38, characterised in that the sealinglip abuts against the cylinder wall.
 40. Damper according to claim 38,characterised in that the first piston part and the sealing lip jointlyform a monolithic body.
 41. Damper according to claim 38, characterisedin that the first piston part and the sealing lip are made from plasticswith different hardnesses.
 42. Damper according to claim 38,characterised in that the first piston part and the sealing lip arewelded together.
 43. Damper according to claim 38, characterised in thatthe first piston part and the sealing lip are glued together.
 44. Damperaccording to claim 32, characterised in that at least a piston part isprovided with a groove running in axial direction on its mantle. 45.Damper according to claim 32, characterised in that the first pistonpart is cylindrical in form in unpressurised condition and the mantle ofsaid piston part adopts a domed shape under pressure.
 46. Damperaccording to claim 32, characterised in that a compression spring isdisposed in the cylinder, said spring rests, firstly, on one front wallof the cylinder and secondly on at least a piston part, wherein theforce of expansion of the elastic piston part is greater than the springforce of the compression spring.
 47. Damper with a cylinder whichcontains a damping fluid and in which a piston, with a piston part whichis forced radially outwards and rubs against the cylinder wall duringthe damping procedure, can be moved linearly, characterised in that thepiston part is made as a solid body of a material with rubber elasticproperties and becomes flattened under pressure whereby it deforms insuch a way that a friction seal is created between the piston part andthe cylinder wall.
 48. Damper according to claim 47, characterised inthat the damper is employed with movable furniture parts.
 49. Damperaccording to claim 47, characterised in that the piston part is madefrom an elastomer.
 50. Damper according to claim 47, characterised inthat the piston part is made from a thermoplastic elastomer (TPE). 51.Damper according to claim 47, characterised in that the piston part ismade from liquid silicon rubber (LSR).
 52. Damper according to claim 47,characterised in that the piston part is made from a silicon rubber. 53.Damper according to claim 47, characterised in that the hardness of atleast a piston part lies between 40 A and 85 Shore.
 54. Damper accordingto claim 47, characterised in that the second piston part is designed asa bolster plate for the first piston part which is connected with apiston rod.
 55. Damper according to claim 47, characterised in that thefirst piston part is provided with a sealing lip.
 56. Damper accordingto claim 55, characterised in that the sealing lip abuts against thecylinder wall.
 57. Damper according to claim 55, characterised in thatthe first piston part and the sealing lip jointly form a monolithicbody.
 58. Damper according to claim 55, characterised in that the firstpiston part and the sealing lip are made from plastics with differenthardnesses.
 59. Damper according to claim 55, characterised in that thefirst piston part and the sealing lip are welded together.
 60. Damperaccording to claim 55, characterised in that the first piston part andthe sealing lip are glued together.
 61. Damper according to claim 47,characterised in that the piston part is provided with a groove runningin axial direction on its mantle.
 62. Damper according to claim 47,characterised in that the first piston part is cylindrical in form inunpressurised condition and the mantle of said piston part adopts adomed shape under pressure.
 63. Damper according to claim 47,characterised in that a compression spring is disposed in the cylinder,said spring rests, firstly, on one front wall of the cylinder andsecondly on at least a piston part, wherein the force of expansion ofthe elastic piston part is greater than the spring force of thecompression spring.